Cooling and exhaust system for a cooking oven

ABSTRACT

The present invention relates to a cooling and exhaust system ( 10 ), in particular for a cooking oven, comprising a fan shroud ( 12 ) and a discharging channel ( 14 ). An impeller ( 16 ) is arranged inside the fan shroud ( 12 ), so that the fan shroud ( 12 ) and the impeller ( 16 ) form a cross-flow fan. The discharging channel ( 14 ) is attached at the fan shroud ( 12 ) and arranged at the circumferential side of the impeller ( 16 ). The discharging channel ( 14 ) includes an open end arranged opposite to the fan shroud ( 12 ). The discharging channel ( 14 ) extends along a horizontal direction. A first inlet ( 20 ) is arranged in an upper portion of the fan shroud ( 12 ), while a second inlet ( 22 ) is arranged in a lower portion of the fan shroud ( 12 ). The first inlet ( 20 ) and the second inlet ( 22 ) are arranged at or close to opposite circumferential sides of the impeller ( 16 ). An outlet ( 24 ) is arranged at the open end of the discharging channel ( 14 ). Further, the present invention relates to a cooking oven with a cooling and exhaust system ( 10 ).

The present invention relates to a cooling and exhaust system, inparticular for a cooking oven. Further, the present invention relates toa cooking oven with a cooling and exhaust system.

Cooling and exhaust systems according to the prior art usually operatewith either an axial fan or cross-flow fan. The cooling and exhaustsystems with the axial fan provide good results in the high efficiencyof a fan shroud. Said fan shroud is able to generate high pressure andan air flow throughout the cooling and exhaust system. However, theaxial fan is expensive and results in high costs of the whole coolingand exhaust system. The cooling and exhaust systems with the cross-flowfan causes only low costs and a good efficiency. The cooling and exhaustsystem with the cross-flow fan is installed above an oven cavity of thecooking oven and directly on a driving plate. A discharging channel ofthe cooling and exhaust system extends from the rear portion to a frontportion of the cooking oven. Vapour and/or hot air are eliminatedthrough the lower part of a control panel of the cooking oven, butsometimes through the upper part of said control panel.

FIG. 6 illustrates a schematic sectional side view of the cooling andexhaust system 40 and a corresponding pressure-space-diagram accordingto the prior art. The upper picture represents the cooling and exhaustsystem 40, while the pressure-space-diagram is shown by the lowerpicture. The cooling and exhaust system 40 comprises a fan shroud 12 anda discharging channel 14. An impeller 16 with a plurality of fan blades18 is arranged inside the fan shroud 12. The rotation axis of theimpeller 16 extends perpendicular to the plane of the drawing, and theimpeller 16 rotates counterclockwise. The fan shroud 12 and the impeller16 form a cross-flow fan. An inlet 42 is arranged above the impeller 16.The impeller 16 is driven by an electric motor. The impeller 16 rotatesin the direction of the action of the forwardly inclined fan blades 18and generates a strong suction of an air stream from the inlet 42. Theair stream follows via a path through the fan shroud 12 and thedischarging channel 14 to an outlet 24.

An exhaust pipe 32 is installed in the bottom of the discharging channel14 and communicates with the ceiling of the oven cavity. By theoperation of the cross-flow fan an air suction and a low pressure zoneoccurs in the exhaust pipe 32, which extracts the vapours from the ovencavity due to the air stream in the discharging channel 14. The vapoursfollow the same path as the air stream from the inlet 42 to the outlet24. The cooling and exhaust system is provided for cooling thecomponents above the oven cavity on the one hand and eliminating thevapours released from the cavity.

The pressure-space-diagram in the lower picture of FIG. 6 shows thedistribution of the static pressure along the cooling and exhaust system40. The static pressure may have positive and negative values. Thedistribution of the static pressure depends on the geometry of the fanshroud 12 and on the inner shapes of the cooling and exhaust system 40.Experimental results have shown that the suction pressure remains lowaround the zone of the exhaust pipe 32 during the operation of thecross-flow fan, since the airflow incident angle relative to thehorizontal base plate 30 has a low value. The low static pressure in thezone of the exhaust pipe 32 is disadvantageous, since a consistent massof vapour remains inside the oven cavity. Further, the low staticpressure in the zone of the exhaust pipe 32 is disadvantageous for theenergy consumption.

It is an object of the present invention to provide an improved coolingand exhaust system, which allows low energy consumption by lowcomplexity and costs.

The object of the present invention is achieved by the cooling andexhaust system according to claim 1.

The cooling and exhaust system according to the present inventioncomprises a fan shroud and a discharging channel, wherein

-   -   an impeller is arranged inside the fan shroud, so that the fan        shroud and the impeller form a cross-flow fan,    -   the discharging channel is attached at the fan shroud and        arranged at the circumferential side of the impeller,    -   the discharging channel includes an open end arranged opposite        to the fan shroud,    -   the discharging channel extends along a horizontal direction,    -   a first inlet is arranged in an upper portion of the fan shroud,    -   a second inlet is arranged in a lower portion of the fan shroud,    -   the first inlet and the second inlet are arranged at or close to        opposite circumferential sides of the impeller, and    -   an outlet is arranged at the open end of the discharging        channel.

The main idea of the present invention is the cooling and exhaust systemwith two inlets and one outlet, wherein the both inlets are arranged atopposite sides of the fan shroud. The inlets suck air from differentdirections. The air is exhausted by the common outlet. The structure oftwo inlets and one outlet allows an efficient operation of the coolingand exhaust system. The impeller may be driven by reduced power.

Preferably, the first inlet is arranged above the discharging channel.This contributes to a compact structure of the cooling and exhaustsystem.

In particular, the direction of an air stream through the first inlet isopposite to the direction of the air stream inside the dischargingchannel.

In contrast, the direction of an air stream through the second inlet maybe the same as the direction of the air stream inside the dischargingchannel.

In a preferred embodiment of the present invention, a bottom side of thefan shroud is at least partially open, wherein a portion of said bottomside is closed or closable by a base plate, and wherein the base plateis either a part of the cooling and exhaust system or of the cookingoven.

Further, the position of the base plate may be variable. Thus, an airstream through the cooling and exhaust system follows a path defined bythe geometry of the cooling and exhaust system in a predeterminedmanner.

In particular, the flow of the air stream through the first inlet isbigger than the flow of the air stream through the second inlet. A mainair stream is sucked through the first inlet, while the second inletsucks an additional air stream.

Moreover, an exhaust pipe may be arranged in the bottom of thedischarging channel, so that the discharging channel is connected orconnectable to an oven cavity of the cooking oven. The structure of thetwo inlets, the one outlet and the exhaust pipe allows a high negativestatic pressure in the discharging channel, so that vapours can beremoved from the oven cavity of the cooking oven and exhausted throughthe discharging channel.

For example, the impeller is driven by an electric motor energized byalternating or direct current.

In particular, the sum of the air streams through the first inlet andthe second inlet is equal to the air stream through the outlet. Thereare no further inlets and outlets.

Furthermore, the present invention relates to a cooking oven with thecooling and exhaust system mentioned above.

Preferably, the first inlet is provided for sucking air from an upperfront portion of the cooking oven.

In particular, the first inlet is provided for sucking air from a spacearound a control panel of the cooking oven.

In contrast, the second inlet is provided for sucking air from the rearside of an oven cavity of the cooking oven.

At last, the base plate may be arranged above the oven cavity of thecooking oven.

Novel and inventive features of the present invention are set forth inthe appended claims.

The present invention will be described in further detail with referenceto the accompanied drawings, in which

FIG. 1 illustrates a schematic sectional side view of a cooling andexhaust system and a corresponding pressure-space-diagram according to apreferred embodiment of the present invention,

FIG. 2 illustrates a schematic perspective view of the cooling andexhaust system according to the preferred embodiment of the presentinvention,

FIG. 3 illustrates a schematic perspective view of the cooling andexhaust system according to the preferred embodiment of the presentinvention,

FIG. 4 illustrates a schematic side view of the cooling and exhaustsystem according to the preferred embodiment of the present invention,

FIG. 5 illustrates a schematic sectional side view of the cooling andexhaust system according to the preferred embodiment of the presentinvention and a further schematic sectional side view of a cooling andexhaust system according to the prior art, and

FIG. 6 illustrates a schematic sectional side view of the cooling andexhaust system and the corresponding pressure-space-diagram according tothe prior art.

FIG. 1 illustrates a schematic sectional side view of a cooling andexhaust system 10 and a corresponding pressure-space-diagram accordingto a preferred embodiment of the present invention. In particular, thecooling and exhaust system 10 is provided for a cooking oven. The upperpicture in FIG. 1 shows the physical cooling and exhaust system 10,while the pressure-space-diagram is shown by the lower picture in FIG.1.

The cooling and exhaust system 10 comprises a fan shroud 12 and adischarging channel 14. The discharging channel 14 is attached at thefan shroud 12. The discharging channel 14 includes an open end oppositeto the fan shroud 12. The discharging channel 14 extends along ahorizontal direction. An impeller 16 is arranged inside the fan shroud12. The impeller 16 includes a plurality of fan blades 18. The rotationaxis of the impeller 16 extends perpendicular to the plane of thedrawing in FIG. 1. The impeller 16 rotates counterclockwise in FIG. 1.The fan blades 18 are inclined in forward direction. The fan shroud 12and the impeller 16 form a cross-flow fan. The impeller 16 is driven byan electric motor 26, which is not shown in FIG. 1. The impeller 16generates a tangential air stream inside the fan shroud 12. Said airstream is set forth inside the discharging channel 14 as a substantiallystraightforward air stream 36. The cooling and exhaust system 10includes a base plate 30 at its bottom. A lower part of the fan shroud12 is formed by a portion of said base plate 30.

The cooling and exhaust system 10 includes a first inlet 20, a secondinlet 22 and an outlet 24. The first inlet 20 is arranged above thejunction of the fan shroud 12 and discharging channel 14. The secondinlet 22 is arranged at the bottom of the fan shroud 12 and at thecircumferential side of the impeller 16. The outlet 24 is arranged atthe open end of the discharging channel 14. The first inlet 20 and thesecond inlet 22 are arranged at opposed circumferential sides of theimpeller 16. The direction of the air flow at the first inlet 20 issubstantially reversed relating to the direction of the air flow at theoutlet 24. In contrast, the direction of the air flow at the secondinlet 22 is substantially the same as the direction of the air flow atthe outlet 24.

A bigger part of the sucked air stream passes the first inlet 20, whilea smaller part of the sucked air stream passes the second inlet 22. Alarge mass of fresh air is sucked by the impeller 16 through the firstinlet 12 and creates a main air stream inside the cooling and exhaustsystem 10. For example, said fresh air is sucked from the space aroundthe control panel of the cooking oven, wherein the air around thecontrol panel is replaced by another fresh air pulled into the ovencasing from the external environment of the cooking oven. The controlpanel and its components may be cooled down by the air from the externalenvironment.

The smaller part of the air stream sucked by the impeller 16 passes thesecond inlet 22. For example, the air stream sucked through the secondinlet 22 is captured from the rear side of an oven cavity of the cookingoven. The air at the rear side of the oven cavity is replaced by freshair pulled in form the external environment above the cooking oven. Theair at the rear side of the oven cavity is generated by heating elementsof the cooking oven and accumulated at said rear side of the ovencavity. The second inlet 22 compensates the difference between the airflows of the outlet 24 and the first inlet 20. Thus, the mass of the airstream circulating in the cooling and exhaust system 10 has permanentlya constant value.

The sum of both air streams from the first inlet 20 and second inlet 22form an air stream 36 inside the discharging channel 14. The air stream36 exhausts through the outlet 24 at the open end of the dischargingchannel 14. The air stream from the second inlet 22 deflects the sum ofboth air streams from the first inlet 20 and second inlet 22, so thatthe direction of said sum of both air streams has an airflow incidentangle 38 with a high value relating to the base plate 30. This is aresult of Bernoulli law, in which the sum of the potential energy,kinetic energy and pressure remains constant along a closed aerodynamicchannel. The air stream from the second inlet 22 contributes todisturbances, a relative low kinetic energy and a relative high negativepressure at the entry of the discharging channel 14.

An exhaust pipe 32 is arranged in the bottom of the discharging channel14. The exhaust pipe 32 is connected or connectable with a ceiling ofthe oven cavity. The air stream from the second inlet 22 causes therelative high negative pressure above the exhaust pipe 32. This resultsin a relative high suction force of the air stream 34 through theexhaust pipe 32. Said high suction force causes of a relative big amountof extracted vapours from the oven cavity. The vapours follow the samepath as the air stream 36 inside the discharging channel 14. The coolingand exhaust system 10 is provided for cooling components above the ovencavity on the one hand and eliminating vapours released from the ovencavity.

The pressure-space-diagram in the lower picture of FIG. 1 shows thedistribution of the static pressure along the cooling and exhaust system10. The static pressure may have positive and negative valuescharacterized by the plus sign and minus sign, respectively. Thedistribution of the static pressure depends on the geometry of the fanshroud 12 and on the inner shapes of the cooling and exhaust system 10.The suction pressure around the zone of the exhaust pipe 32 is relativehigh during the operation of the cross-flow fan, since the airflowincident angle 38 relative to the horizontal base plate 30 has a highvalue. The high static pressure in the zone of the exhaust pipe 32 is anadvantage of the present invention, since a lot of vapour is removedfrom the oven cavity. Further, the high static pressure in the zone ofthe exhaust pipe 32 is advantageous for the energy consumption.

FIG. 2 illustrates a schematic perspective view of the cooling andexhaust system 10 according to the preferred embodiment of the presentinvention. FIG. 2 clarifies the geometric structure of the cooling andexhaust system 10. In the perspective view of FIG. 2 the dischargingchannel 14 is shown in front of the fan shroud 12.

The cooling and exhaust system 10 comprises the fan shroud 12 and thedischarging channel 14 attached at said fan shroud 12. The outlet 24 isarranged at the open end of the discharging channel 14. The impeller 16is arranged inside the fan shroud 12. The fan blades 18 of the impeller16 are partially visible through the first inlet 20. The electric motor26 is arranged beside the fan shroud 12.

The electric motor 26 is energized at different voltages. For example,the electric motor 26 is energized by an alternating current at voltagesfrom 110 V to 240 V. Further, the electric motor 26 may be alsoenergized by direct current. For example, the electric power of theseelectric motors 26 may be vary between 10 W and 45 W. The electric powerof the electric motor 26 depends on the current requests. Preferably,the electric motor 26 is of a shaded pole type or a squirrel cage type.

FIG. 3 illustrates a schematic perspective view of the cooling andexhaust system 10 according to the preferred embodiment of the presentinvention. In the perspective view of FIG. 3 shows that side of the fanshroud 12, at which the electric motor 26 is attached.

FIG. 4 illustrates a schematic side view of the cooling and exhaustsystem 10 according to the preferred embodiment of the presentinvention.

The discharging channel 14 attached at said fan shroud 12. The outlet 24is arranged at the open end of the discharging channel 14. The impeller16 is arranged inside the fan shroud 12. The fan blades 18 of theimpeller 16 are partially visible through the first inlet 20. Theelectric motor 26 is arranged beside the fan shroud 12, but not visiblein FIG. 4. The first inlet 20 and the second inlet 22 are arranged atthe opposed circumferential sides of the fan shroud 12.

FIG. 5 illustrates a schematic sectional side view of the cooling andexhaust system 10 according to the preferred embodiment of the presentinvention and a further schematic sectional side view of a cooling andexhaust system 40 according to the prior art. An upper picture in FIG. 5shoes the cooling and exhaust system 40 according to the prior art,while a lower upper picture in FIG. 5 shows the cooling and exhaustsystem 10 according to the present invention. The cooling and exhaustsystem 10 according to the preferred embodiment is compared with coolingand exhaust system 40 of the prior art.

The discharging channels 14 of the present invention and the prior arthave different heights 28 and 46. A height 28 of the discharging channel14 of the inventive cooling and exhaust system 10 is bigger than acorresponding height 46 of the discharging channel 14 of the inventivecooling and exhaust system 40 according to the prior art. In order toavoid unwanted vibrations generated by induction, the electric motor 26should be arranged at a minimum height. Preferably, the distance betweenthe electric motor 26 and the bottom of the base plate 30 should be atleast 10 mm. The residual dimensions of the both cooling and exhaustsystems 10 and 40 are substantially the same.

FIG. 6 illustrates a schematic sectional side view of the cooling andexhaust system 40 and the corresponding pressure-space-diagram accordingto the prior art. The upper picture represents the cooling and exhaustsystem 40, while the pressure-space-diagram is shown by the lowerpicture. The cooling and exhaust system 40 comprises the fan shroud 12and the discharging channel 14. The impeller 16 with the plurality offan blades 18 is arranged inside the fan shroud 12. The rotation axis ofthe impeller 16 extends perpendicular to the plane of the drawing. Theimpeller 16 rotates counterclockwise. The fan shroud 12 and the impeller16 form the cross-flow fan. An inlet 42 is arranged above the impeller16. The impeller 16 is driven by the electric motor. The impeller 16rotates in the direction of the action of the forwardly inclined fanblades 18 and generates the strong suction of an air stream from theinlet 42. The air stream follows via the path through the fan shroud 12and the discharging channel 14 to the outlet 24.

The exhaust pipe 32 is installed in the bottom of the dischargingchannel 14 and communicates with the ceiling of the oven cavity. By theoperation of the cross-flow fan the air suction and low pressure zoneoccurs in the exhaust pipe 32, which extracts the vapours from the ovencavity due to the air stream in the discharging channel 14. The vapoursfollow the same path as the air stream from the inlet 42 to the outlet24. Also the cooling and exhaust system 40 is provided for cooling thecomponents above the oven cavity on the one hand and eliminating thevapours released from the cavity.

The pressure-space-diagram in the lower picture of FIG. 6 shows thedistribution of the static pressure along the cooling and exhaust system40. The static pressure has positive and negative values. Thedistribution of the static pressure depends on the geometry of the fanshroud 12 and on the inner shapes of the cooling and exhaust system 40.The suction pressure remains low around the zone of the exhaust pipe 32during the operation of the cross-flow fan, since the airflow incidentangle 44 relative to the horizontal base plate 30 has a low value. Thelow static pressure in the zone of the exhaust pipe 32 isdisadvantageous, since a consistent mass of vapour remains inside theoven cavity. Further, the low static pressure in the zone of the exhaustpipe 32 is disadvantageous for the energy consumption.

Although an illustrative embodiment of the present invention has beendescribed herein with reference to the accompanying drawings, it is tobe understood that the present invention is not limited to that preciseembodiment, and that various other changes and modifications may beaffected therein by one skilled in the art without departing from thescope or spirit of the invention. All such changes and modifications areintended to be included within the scope of the invention as defined bythe appended claims.

LIST OF REFERENCE NUMERALS

-   10 cooling and exhaust system-   12 fan shroud-   14 discharging channel-   16 impeller-   18 fan blade-   20 first inlet-   22 second inlet-   24 outlet-   26 electric motor-   28 height of the discharging channel 14-   30 base plate-   32 exhaust pipe-   34 air stream through the exhaust pipe 32-   36 air stream inside the discharging channel 14-   38 airflow incident angle inside the discharging channel 14-   40 cooling and exhaust system of the prior art-   42 inlet-   44 airflow incident angle inside the discharging channel 14-   46 height of the discharging channel 14-   P pressure-   l length

1. A cooling and exhaust system, in particular for a cooking oven,comprising a fan shroud and a discharging channel, wherein an impelleris arranged inside the fan shroud, so that the fan shroud and theimpeller form a cross-flow fan, the discharging channel is attached atthe fan shroud and arranged at the circumferential side of the impeller,the discharging channel includes an open end arranged opposite to thefan shroud, the discharging channel extends along a horizontaldirection, a first inlet is arranged in an upper portion of the fanshroud, a second inlet is arranged in a lower portion of the fan shroud,the first inlet and the second inlet are arranged at or close toopposite circumferential sides of the impeller, and an outlet isarranged at the open end of the discharging channel.
 2. The cooling andexhaust system according to claim 1, characterized in that the firstinlet is arranged above the discharging channel.
 3. The cooling andexhaust system according to claim 1, characterized in that the directionof an air stream through the first inlet is opposite to the direction ofthe air stream inside the discharging channel.
 4. The cooling andexhaust system according to claim 1, characterized in that the directionof an air stream through the second inlet is the same as the directionof the air stream inside the discharging channel.
 5. The cooling andexhaust system according to claim 1, characterized in that a bottom sideof the fan shroud is at least partially open, wherein a portion of saidbottom side is closed or closable by a base plate, and wherein the baseplate is a part of the cooling and exhaust system or of the cookingoven.
 6. The cooling and exhaust system according to claim 5,characterized in that the position of the base plate is variable, sothat an air stream through the cooling and exhaust system follows a pathdefined by the geometry of the cooling and exhaust system in apredetermined manner.
 7. The cooling and exhaust system according toclaim 1, characterized in that the flow of the air stream through thefirst inlet is bigger than the flow of the air stream through the secondinlet.
 8. The cooling and exhaust system according to claim 1,characterized in that an exhaust pipe is arranged in the bottom of thedischarging channel so that the discharging channel is connected orconnectable to an oven cavity of the cooking oven.
 9. The cooling andexhaust system according to claim 1, characterized in that the impelleris driven by an electric motor energized by alternating or directcurrent.
 10. The cooling and exhaust system according to claim 1,characterized in that the sum of the air streams through the first inletand the second inlet is equal to the air stream through the outlet. 11.A cooking oven with a cooling and exhaust system, characterized in thatthe cooking oven comprises the cooling and exhaust system according toclaim
 1. 12. The cooking oven according to claim 11, characterized inthat the first inlet is provided for sucking air from an upper frontportion of the cooking oven.
 13. The cooking oven according to claim 12,characterized in that the first inlet is provided for sucking air from aspace around a control panel of the cooking oven.
 14. The cooking ovenaccording to claim 11, characterized in that the second inlet isprovided for sucking air from the rear side of an oven cavity of thecooking oven.
 15. The cooking oven according to claim 11, characterizedin that a bottom side of the fan shroud is at least partially open,wherein a portion of said bottom side is closed or closable by a baseplate, wherein the base plate is arranged above an oven cavity of thecooking oven.